Field of the Invention
The invention relates to the technical field of underground medium development, such as gas reservoir development (gas storage/withdrawal, gas exploitation) and monitoring of these operations (contamination of operations on aquifers). The invention notably relates to the field of geological storage site monitoring for gases such as carbon dioxide (CO2) or methane. In particular, the invention relates to fluid sampling devices and more particularly to a device for sampling fluids under pressure in a well, a pipe, a tube, a conduit or the like.
Description of the Prior Art
Fluids present in wells often need to be sampled in order to determine their composition to characterize the geological reservoirs reached by the borehole. This is notably the case for geological gas storage site monitoring.
Industrialists have developed many techniques allowing the evolution of fluids injected into porous media to be monitored.
Geochemical monitoring methods for geological CO2 storage sites, based on the study of volatile species, are for example known. These methods are described in French Patent Nos. 2,972,758 and 2,974,358.
These methods essentially apply to two compartments which are reservoirs/saline aquifers where the main objective is to quantify the dissolved and precipitated CO2, and thus to establish a real mass balance, and aquifers overlying the cap rock, where the main objective is to diagnose a leak as early as possible.
To implement these methods, it is thus necessary to have a device for sampling fluids under pressure in a well drilled through a geological formation. Such a device is referred to as sampler.
Samplers known as FTS (Flow-Through Sampler), allow obtaining fluid samples from a well drilled through a geological formation. Such a device is comprised of a sample chamber with a spring-loaded valve at each end. A latching mechanism connects the valves together and holds them open. A clock for programming the closing time and a triggering mechanism for releasing the valves are arranged above the chamber. The lower end is provided with means allowing the fluid to enter. A rope socket for attaching a cable is arranged at the top.
U.S. Pat. No. 5,945,611 discloses a device for sampling fluids under pressure in a pipe, a tube, a conduit or the like. This device comprises a plurality of pistons, a body having a common passageway, wherein the pistons are slidably mounted and a lateral inlet and a lateral outlet port are located within the passageway and communicate with the pipeline. The inlet and outlet ports are arranged so that the motion of the pistons covers and uncovers the inlet and outlet ports.
U.S. Pat. No. 5,896,926 discloses a device for in-situ sampling of groundwater under static conditions without disturbing the environment which comprises a packer to isolate the sampling system from the area located above, as well as an in-situ pumping system in the sampler for “sucking” the fluid into the sample chamber.